A detection device of the impact pressure of door closing of an automobile comprises a pressure sensor, a transient peak processing circuit, an A/D (Analog to Digital) converter, a microprocessor and an output unit; the pressure sensor is used for detecting the pressure in the automobile and outputting an analog signal corresponding to the pressure in size; the output analog signal is input to the microprocessor after being processed through the transient peak processing circuit and the A/D converter in turn; the result output is performed through the output unit after the analog signal is processed through the microprocessor; the output analog signal can be amplified and the instantaneous peak voltage can be maintained through the transient peak processing circuit. According to the detection device of the impact pressure of the door closing of the automobile, the size of the impact pressure difference produced before and after the door closing of the automobile can be timely detected, the digital display can be performed on the detected pressure difference, the detected pressure difference can also be displayed in the form of a curved line, the size of the peak can be marked, detection results can be printed through a micro-printer, and accordingly the display is intuitive and the use is convenient.